Table 1.

Gestational age estimation.

	Sweeps collected by sonographers		Sweeps collected by novices
	Standard ultrasound device	Low-cost handheld device	Standard ultrasound device	Low-cost handheld device
Number	406	104	112	56
Blind-sweep MAE ± sd (days)	3.8 ± 3.6	3.3 ± 2.8	4.4 ± 3.5	5.0 ± 4.0
Standard fetal biometry estimates MAE ± sd (days)	5.2 ± 4.6	3.8 ± 3.6	4.8 ± 3.7	4.7 ± 4.0
Blind sweep—standard fetal biometry mean difference ± sd (days)	−1.4 ± 4.5	−0.6 ± 3.8	−0.4 ± 4.8	0.4 ± 5.1
MAE difference 95% CI (days)	−1.8, −0.9	−1.3, 0.1	−1.3, 0.5	−1.0, 1.7
Blind sweep ME ± sd (days)	−0.9 ± 5.3	0.4 ± 4.4	−1.5 ± 5.5	−3.8 ± 5.4
Standard fetal biometry estimates ME ± sd (days)	−1.4 ± 7.0	−0.25 ± 5.4	−2.6 ± 5.3	−3.4 ± 5.2
Reduced blind-sweep protocol MAE ± sd (days)	4.0 ± 3.7	3.5 ± 3.0	4.5 ± 3.5	5.1 ± 4.2

Mean absolute error (MAE) and mean error (ME) between gestational age (GA) estimated using the blind-sweep procedure and ground truth, and the MAE and ME between the GA estimated using the standard fetal biometry ultrasound procedure and ground truth. One visit by each participant eligible for each subgroup was selected at random. The reduced blind-sweep protocol (last row) included only two blind sweeps. All other blind-sweep results used a set of six blind sweeps per patient visit. All fetal biometry GA estimates were collected by expert sonographers using standard ultrasound devices.